Weight scales systems and methods

ABSTRACT

A weight scale system for measuring the weight of an object includes a bed section, a vertical separator actuator and a controller. The bed section includes a lower-platform, an upper-platform and weight sensor assemblies located on the lower-platform, each includes at least one weight sensor. The bed section further includes at least one vertical-separator. The vertical-separator actuator is coupled with the vertical-separator and with the controller. The controller is further coupled with the weight sensors. The controller directs the vertical-separator actuator to operate the bed section in at least two modes, a referencing mode in which the vertical-separator detaches the upper-platform from the weight sensor assemblies, thereby enabling referencing the weight sensors, and a weighing mode, in which the vertical separator re-attaches the upper-platform with the weight sensor assemblies, such the that the weight associated with the upper-platform is fully applied on the weight sensors.

FIELD OF THE DISCLOSED TECHNIQUE

The disclosed technique relates to weight scales in general, and tosystems and methods for weight scales systems for hospital beds inparticular.

BACKGROUND OF THE DISCLOSED TECHNIQUE

Weighing immobile object, specifically objects which cannot be lifted bya human may be challenging, for example, weighing patients on a hospitalbed. Known in the art techniques include placing an inflatable mattressunder the patient. A further challenge is referencing the weight scales.

PCT Application Publication WO 1990/002927 to Broomé, entitled “Methodand device for weighing, especially of seriously ill patients confinedto bed” describes a system for determining the weight of a patientconfined to a bed. The system includes an inflatable mattress, acompressor, a compressed air container and pressure sensors. Theinflatable mattress is laced beforehand an inflatable mattress in thebed under the patient. When weighing is carried out, the mattress isinflated with compressed air until the patient is balanced. Thecompressed-air supply is interrupted, and a previously measured exactquantity of air is supplied to the mattress. The change of pressurecaused by the patient's load on the exact quantity of air supplied tothe mattress is measured and converted into weight. The exact quantityof air supplied by filling the compressed air container until thepressure therein reaches a predetermined level. The air in the containeris then transferred to the inflatable mattress.

U.K. Patent GB2453371B to Robinson, entitled “Mattress pump apparatuscontroller, mattress pump apparatus, mattress and method of controllinga mattress” directs to a system which detects when a weight is placed onthe mattress and then determines the weight of the mattress. To thatend, the mattress is filled to a predetermined initial pressure. When aload is placed on the mattress, a change in the pressure is detected.This change relates to the weight of the patient.

U.S. Pat. No. 5,861,582 to Flanagan et al, entitled “Patient weighingsystem” directs to a patient weighing system which includes load sensingcasters or load lift modules installed on a hospital bed. The castersand load lift modules each include pneumatic lifts. The lifts areoperative to load and unload the weight of the device onto apiezoelectric load cells. The load cells are electrically connected tocontrol units which include visual displays. In operation, the operatorthen pumps a foot pedal to pressurize the pneumatic lines and to expandchambers in each of the housings. This unloads the load cells. Afterwaiting a brief period of time which relates to the discharge time ofthe load cells, the processor resets itself so that the signal from eachload cell is considered to be a zero value.

SUMMARY OF THE PRESENT DISCLOSED TECHNIQUE

It is an object of the disclosed technique to provide a novel weightscale system and method system for measuring the weight of at least oneobject. In accordance with the disclosed technique, there is thusprovided a system for measuring the weight of at least one object. Theweight scale system includes a bed section, vertical separator actuatorand a controller. The bed section includes a lower platform, an upperplatform for bearing the weight of the at least one object, at least oneweight sensor assembly and at least one vertical separator. The at leastone weight sensor assembly includes at least one weight sensor, and islocated on the lower platform. The at least one weight sensor isoperable to measure weight applied thereon. The at least one verticalseparator is operable to detach the upper platform from the at least oneweight sensor assembly. The at least one vertical separator actuator iscoupled with the vertical separator and is operable to operate thevertical separator. The controller is coupled with the at least oneweight sensor and with the vertical separator actuator. The controllerdirects the vertical separator actuator to operate the bed section in atleast two modes, a referencing mode and a weighing mode. In thereferencing mode the vertical separator detaches the upper platform fromthe at least one weight sensor assembly, thereby enabling thereferencing of the at least one weight sensor. In the weighing mode thevertical separator re-attaches the upper platform with the at least oneweight sensor assembly, such that the weight associated with the upperplatform is fully applied on the at least one weight sensor.

In accordance with another aspect of the disclosed technique, there isthus provided a method for referencing at least one weight sensor in aweight scale system. The method incudes the procedures of detaching anupper platform of a bed section of a weight scale from the at least onesensor such that no weight is applied on the at least one weight sensorand referencing the at least one weight sensor. The bed section includesa lower platform, the upper platform bearing the weight of at least oneobject and the at least one weight sensor. The at least one weightsensor is located on the lower platform and operable to measure weightapplied thereon. The method further includes the procedure ofre-attaching the upper platform to the at least one weight sensor suchthat the upper platform and the load thereon apply their full weight onthe at least one weight sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosed technique will be understood and appreciated more fullyfrom the following detailed description taken in conjunction with thedrawings in which:

FIG. 1 is a schematic illustration of a weighing scenario, in accordancewith an embodiment of the disclosed technique;

FIG. 2, is a schematic illustration of a mattress weight scales systemconstructed and operative in accordance with another embodiment of thedisclosed technique;

FIG. 3 is a schematic illustration of method for measuring the weight ofan object, placed on top of a mattress weight scale, operative inaccordance with a further embodiment of the disclosed technique;

FIGS. 4A-4D are schematic illustrations of a mattress weight scalessystem, constructed and operative in accordance with another embodimentof the disclosed technique;

FIGS. 5A-5D are schematic illustrations of a valve assembly connected toa pump, in accordance with a further embodiment of the disclosedtechnique;

FIGS. 6A-6D are schematic illustrations of a weighing mattress,constructed and operative in accordance with another embodiment of thedisclosed technique;

FIG. 7 is a schematic illustration of a weighing mattress, constructedand operative in accordance with a further embodiment of the disclosedtechnique;

FIG. 8 is a schematic illustration of a weighing mattress, constructedand operative in accordance with another embodiment of the disclosedtechnique;

FIG. 9 is a schematic illustration of a weighing mattress, in accordancewith a further embodiment of the disclosed technique;

FIGS. 10A, 10B and 10C are schematic illustrations of a weight scalessystem, constructed and operative in accordance with another embodimentof the disclosed technique;

FIGS. 11A, 11B and 11C are schematic illustration of an exemplary bedsection, constructed and operative in accordance with a furtherembodiment of the disclosed technique;

FIGS. 12A and 12B are a schematic illustration of an exemplary bedsection, constructed and operative in accordance with another embodimentof the disclosed technique;

FIG. 13A is a schematic illustration of an exemplary bed section,constructed and operative in accordance with a further embodiment of thedisclosed technique;

FIG. 13B is a schematic illustration of an exemplary weight sensors,constructed and operative in accordance with a further embodiment of thedisclosed technique; and

FIG. 14 is a schematic illustration of a weight scale system,constructed and operative in accordance with another embodiment of thedisclosed technique; and

FIG. 15 is a schematic illustration of a method for referencing weightsensors in a bed section, operative in accordance with a furtherembodiment of the disclosed technique.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The disclosed technique overcomes the disadvantages of the prior art byproviding a system and method for determining the weight of immobileobjects, specifically patients lying on a bed. According to thedisclosed technique, a weighing mattress is placed between the bedplatform and the bed mattress. The weighing mattress includes weighingsegments and reference segments. The weighing segments and the referencesegments are full with a fluid. The weighing segments are all fluidallycoupled with each other and with a weight sensor. The reference segmentsare all fluidally coupled with each other and with a reference sensor.The weighing segments and the reference segments are mechanicallycoupled therebetween. The weight sensor measures the pressure of thefluid in weighing segments. The reference sensor measures the pressureof the fluid in reference segments. A processor subtracts the referencepressure form the weighing pressure to determine a difference pressureand determines the weight of the object placed on top of the bedaccording to this difference pressure. According to the disclosedtechnique, and as further elaborated below, the weight of the object isnot applied on reference segments. Thus, the pressure in the referencesegments is only affected by changes in environmental conditions.Subtracting the reference pressure from the weighing pressure alleviatesthe effects of the environmental conditions on the pressure of the fluidin the weighing segments

Reference is now made to FIG. 1, which is a schematic illustration of aweighing scenario, generally referenced 100, in accordance with anembodiment of the disclosed technique. In scenario 100, a patient 102lies on a bed 104, on top of a mattress 106. A weighing mattress 108 islocated between the platform 110 of bed 104 and mattress 106. Scales 112measure the weight of patient 102, as further elaborated below. Scales112 may indicate to a user the weight of patient 102. For example,scales 112 present the weight of patient 112 on a display.

Reference is now made to FIG. 2, which is a schematic illustration of amattress weight scales system, generally referenced 150, constructed andoperative in accordance with another embodiment of the disclosedtechnique. Mattress weight scales system 150 includes a weighingmattress 152, a weight sensor 154, a reference sensor 156, a processor158, and a weight indicator 160. Weighing mattress 152 includes aplurality of weighing segments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N) anda plurality of reference segments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M),where N and M are integers.

Reference segments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M) are interleavedbetween weighing segments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N) alongthe mattress. FIG. 2 depicts the cross section of weighing segments 164₁, 164 ₂, 164 ₃, . . . , 164 _(N) and reference segments 166 ₁, 166 ₂,166 ₃, . . . , 166 _(M). In FIG. 2, weighing segments 164 ₁, 164 ₂, 164₃, . . . , 164 _(N) and reference segments 166 ₁, 166 ₂, 166 ₃, . . . ,166 _(M) are exemplified as tubes. In the example depicted in FIG. 2,the thickness of weighing segments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N)is larger than the thickness of reference segments 166 ₁, 166 ₂, 166 ₃,. . . , 166 _(M). When weighing segments 164 ₁, 164 ₂, 164 ₃, . . . ,164 _(N) and reference segments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M)are embodied as tubes, the diameter weighing segments 164 ₁, 164 ₂, 164₃, . . . , 164 _(N) is larger than the diameter of reference segments166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M).

Each one of weighing segments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N) andreference segments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M) is full with afluid (e.g., water, oil, gas). Weight sensor 154 and reference sensors156 are typically fluid pressure transducers converting pressure appliedon the sensor to a corresponding electrical signal. Weight indicator 160is, for example, a display which presents the user with a numericalrepresentation of the weight of the object being weighted. As a furtherexample, weight indicator 160 a sound indicator producing a sounduttering the weight of the object.

In the example brought forth in FIG. 2, weighing segments 164 ₁, 164 ₂,164 ₃, . . . , 164 _(N) are mechanically coupled with reference segments166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M). Weighing segments 164 ₁, 164 ₂,164 ₃, . . . , 164 _(N) are fluidally coupled therebetween. The term‘fluidally coupled’ relates herein to the ability of fluid to freelyflow between the segments and components. Reference segments 166 ₁, 166₂, 166 ₃, . . . , 166 _(M) are also fluidally coupled therebetween. Itis, however, noted that weighing segments 164 ₁, 164 ₂, 164 ₃, . . . ,164 _(N) are not fluidally coupled with reference segments 166 ₁, 166 ₂,166 ₃, . . . , 166 _(M). Furthermore, weighing segments 164 ₁, 164 ₂,164 ₃, . . . , 164 _(N) are fluidally coupled with weight sensor 154.Reference segments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M) are fluidallycoupled with reference sensor 156. Processor 158 is coupled with weightsensor 154, reference sensor 156, and weight indicator 160.

Weight sensor 154 measures the pressure of the fluid in weighingsegments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N) and provides processor152 with a signal indicative of the measured pressure. Similarlyreference sensor 156 measures the pressure of the fluid in referencesegments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M) and provides processor158 with a signal (e.g., electric voltage or electric current)indicative of the measured pressure. The term ‘measure’ relates hereinto the process converting pressure applied on the sensor to anelectrical signal corresponding to a pressure applied on either weightsensor 154 or reference sensor 156. The term ‘measurement’ refers hereinto the signal relating to the pressure in either weight sensor 154 orreference sensor 156 (i.e., either the signal produced by weight sensor154 and reference sensor 156 or a sampled version thereof). Themeasurement from weight sensor 154 is referred to herein as ‘theweighing measurement’ and the measurement form reference sensor 156 isreferred to herein as ‘the reference measurement’. Also the pressure inweighing segments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N) is referred toherein as ‘the weighing pressure’ and the pressure in in referencesegments 166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M) is referred to as ‘thereference pressure’

When measuring the weight of an object (e.g., a patient), the object isplaced on top weighing mattress 152. However, weighing segments 164 ₁,164 ₂, 164 ₃, . . . , 164 _(N) are affected by the weight of the object.The change in pressure of the fluid in weighing segments 164 ₁, 164 ₂,164 ₃, . . . , 164 _(N) relates to the weight of the object as well asto effects of environmental conditions. However, the effects of theenvironmental conditions (i.e., at least of ambient temperature) on themeasurements are unknown. Furthermore, the inventors have discoveredthat these environmental effects are not uniform along the length of theweighing mattress. Since the reference segments are not affected by theweight of the object, the pressure of the fluid in these segments isaffected only by the change in environmental conditions along themattress. To determine the weight of the object on top of weighingmattress 152, processor 158 subtracts the reference measurement from theweighing measurement and determines the weight of the object on weighingmattress 152 therefrom as further explained below. Thus, processor 158alleviates the effects of the environmental condition on the weighingmeasurement. In other words, processor 158 determines a differencemeasurement by subtracting the reference measurement from the weighingmeasurement and determines the weight of the object on weighing mattress152 according to this difference measurement as further explained below.

Prior to use, mattress weight scale system 150 is calibrated todetermine a correspondence between the difference measurement determinedfrom the weighing measurement and the reference measurement, and theweight of the object on top of weighing mattress 152. To that end, eachof a plurality of objects of different known weights is placedseparately on weighing mattress 152, and processor 158 determines arespective difference measurement as explained above. Processor 158 alsodetermines a difference measurement when no weight is placed on weighingmattress 152. Since the weights placed on weighing mattress 152 areknown, a correspondence is determined between the difference measurementrespective of each weight and the respective weight. This correspondenceis employed to determine the weight of the object on top of weighingmattress 152 according to the determined difference measurement. Thiscorrespondence may take the form of a Look Up Table (LUT).Alternatively, a curve may be fitted to the measured weights andcorresponding difference measurements. The environmental conditionsduring the calibration should be within the designed operational rangeof the mattress weight scale.

Reference is now made to FIG. 3, which is a schematic illustration ofmethod for measuring the weight of an object, placed on top of amattress weight scale, operative in accordance with a further embodimentof the disclosed technique. In procedure 180, the pressure in thepressure in the weighing segments is measured. With reference to FIG. 2,weight sensor 154 measures the pressure in the weighing segments.

In procedure 182, the pressure in the reference segments are measured.With reference to FIG. 2, weight sensor 156 measures the pressure in theweighing segments.

In procedure 184, the reference segments measurement is subtracted fromthe weighing segments measurement to determine a difference measurement.With reference to FIG. 2, processor 158 subtracts the referencemeasurement from the weighing measurement.

In procedure 186, the weight of the object is determined from thedifference measurement. The weight of the object is determined from thedifference measurement, according to a correspondence between variousdifferent weights and a corresponding difference measurement. Thiscorrespondence is determined before using the mattress weight scale.With reference to FIG. 2, processor 158 determines the weight of theobject according to the difference measurement

When the fluid employed in the weighing and reference segments is gas,the gas inside the segments may leak between measurements either fromthe weighing segments, or from reference segments, or from both. Thesevariations in the amount of re-filled gas may result in variations inthe pressure of the gas inside the mattress weight scale, which mayresult in ambiguity in the determined weight. To alleviate thisambiguity, the weighing mattress of a mattress weight scales systemshould be refilled with gas before each weighing. To that end, are-filling mechanism is connected to the weighing and referencesegments.

Reference is now made to FIGS. 4A-4D, which are schematic illustrationsof a mattress weight scales system, generally referenced 200,constructed and operative in accordance with another embodiment of thedisclosed technique. Mattress weight scales system 200 includes aweighing mattress 202, a valves assembly 204 and a pump 206. Mattressweight scales system 200 further includes a weight sensor 208, areference sensor 210 a processor 212, and a weight indicator 212.Weighing mattress 202 includes a plurality of weighing segments 218 ₁,218 ₂, 218 ₃, . . . , 218 _(N) and a plurality of reference segments 220₁, 220 ₂, 220 ₃, . . . , 220 _(M) where N and M are integers. Valveassembly 204 includes values 224, 226, 228, 230, 232 and 234. In theexample brought forth in FIGS. 4A-4D, valve assembly 204 is depicted asincluding six two-way values. However, valve assembly 204 may beconfigured with three, three-way valves. Also, for the sake ofsimplicity of the explanation which follows, the ports of each one oftwo-way valves 224, 226, 228, 230, 232 and 234 are number in FIGS.4A-4D, 1 and 2

Weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) and referencesegments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) are similar to weighingsegments 164 ₁, 164 ₂, 164 ₃, . . . , 164 _(N) and reference segments166 ₁, 166 ₂, 166 ₃, . . . , 166 _(M) described hereinabove inconjunction with FIG. 2. As such, reference segments 220 ₁, 220 ₂, 220₃, . . . , 220 _(M) are interleaved between weighing segments 218 ₁, 218₂, 218 ₃, . . . , 218 _(N) along the mattress. FIGS. 4A-4D depicts thecross section of weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N)and reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M). In FIGS.4A-4D, weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) andreference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) are exemplifiedas tubes. In the example depicted in Figures . . . , the thickness ofweighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) is larger thanthe thickness of reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220_(M).

Each one of weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) andreference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) is full with afluid (e.g., water, oil, gas). Weight sensor 208 and reference sensors210 are typically fluid pressure transducers converting pressure appliedon the sensor to a corresponding electrical signal. Weight indicator 214is, for example, a display which presents the user with a numericalrepresentation of the weight of the object being weighted. As a furtherexample, weight indicator 214 a sound indicator producing a sounduttering the weight of the object.

Also similar to as described above in conjunction with FIG. 2, weighingsegments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) are mechanically coupledwith reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M). Weighingsegments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) are fluidally coupledtherebetween. The term ‘fluidally coupled’ relates herein to the abilityof fluid to freely flow between the segments and components. Referencesegments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) are also fluidallycoupled therebetween. It is, however, noted that weighing segments 218₁, 218 ₂, 218 ₃, . . . , 218 _(N) are not fluidally coupled withreference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M). Furthermore,weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) are fluidallycoupled with weight sensor 208. Reference segments 220 ₁, 220 ₂, 220 ₃,. . . , 220 _(M) are fluidally coupled with reference sensor 210.Processor 212 is coupled with pump 206, weight sensor 208, referencesensor 210, and weight indicator 212. Furthermore, weighing segments 218₁, 218 ₂, 218 ₃, . . . , 218 _(N) and reference segments 220 ₁, 220 ₂,220 ₃, . . . , 220 _(M) are fluidally coupled with valve assembly 204.Specifically, in the example brought forth in FIGS. 4A-4D, port 1 ofvalve 228 and port 2 of valve 234 are fluidally coupled with a gasreservoir (e.g., ambient air-not shown). The output port of pump 206,port 2 of valve 228 and port 2 of valve 226 are fluidally coupledtherebetween. The input port of pump 206, port 1 of valve 223 and port 1of valve 260 are fluidally coupled therebetween. Port 2 of valve 230,reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) and port 1 ofvalve 232 are fluidally there between. Port 2 of valve 224, port 1 ofvalve 226 and port 2 of valve 232 are fluidally coupled therebetween.Port 1 of valve 224 is fluidally coupled with weighing segments 218 ₁,218 ₂, 218 ₃, . . . , 218 _(N).

As mentioned above, prior to measuring the weight of the object, andoptionally while the object is placed on top weighing mattress 202,weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) are filled gasby filling reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) withgas until the gas in reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220_(M) reaches a predetermined pressure, and transferring the gas weighingsegments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N). This may be repeated fora predetermined number of times. Each filling of reference segments 220₁, 220 ₂, 220 ₃, . . . , 220 _(M) with gas, and the transfer of gas toweighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) is referred toherein as a ‘filling cycle’. After completing the predetermined numberof filling cycles, reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220_(M) are once again filled with gas until the gas therein reaches thepredetermined pressure. A filling cycle and the filling of referencesegments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) once again with gas,until the gas therein reaches the predetermined pressure, is referred toherein as ‘filling the mattress’

Similar to as described above, the pressure of the gas in referencesegments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) is measured by referencesensor 210 which provides the weighing measurement to processor 212. Theabove predetermined pressure serves as the reference pressure as well.Thereafter, weight sensor 208 measures the weighing pressure when theobject is placed on top of weighing mattress 202 and provides theweighing measurement to processor 212. Processor 212 subtracts thereference measurement from the weighing measurement to determine adifference measurement. Processor 212 determines the weight of theobject according to a correspondence between various the differencemeasurements and respective weights (i.e., similar to as describedabove). It is noted that the same number of filling cycles should beemployed when determining the weight of the object on top of weighingmattress 202 and when determining the correspondence between various thedifference measurements and respective weights. It is further notedthat, similar to as described above in conjunction with FIG. 2, sinceonly weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) areaffected by the weight of the object, the change in pressure of thefluid in weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) relatesto the weight of the object as well as to effects of environmentalconditions. Since reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220_(M) are not affected by the weight of the object, the pressure of thefluid in these segments is affected only by the change in environmentalconditions along the mattress. By subtracting the reference measurementform the weighing measurement, processor 202 alleviates the effects ofthe unknown environmental conditions on the weighing measurement.

As mentioned above, prior to weighing the object a predetermined numberof filling cycles are performed to fill weighing segments 218 ₁, 218 ₂,218 ₃, . . . , 218 _(N) with gas, after which reference segments 220 ₁,220 ₂, 220 ₃, . . . , 220 _(M) are filled with gas until the gas thereinreaches a predetermined pressure. Following is a description of fillingthe mattress. With reference to FIG. 4A, initially any residual gas isemptied from weighing mattress (i.e., from both weighing segments 218 ₁,218 ₂, 218 ₃, . . . , 218 _(N) and reference segments 220 ₁, 220 ₂, 220₃, . . . , 220 _(M)). To that end, processor 212 directs valves 226 and234 to the open state thereof and directs valves 224, 228, 230 and 232to the closed state thereof. The open state relates to a state where nofluid can flow between the ports of the valve. The closed state,indicated by a double headed arrow, relates to a state where fluid canflow between the ports of the valve marked by the doubled headed arrow.Processor 212 then activates pump 206. The gas from weighing segments218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) flows through valves 224, 232,230, through pump 206 and through valve 224 to the gas reservoir. Thegas from reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) flowsthrough valves 230, through pump 206 and through valve 224 to the gasreservoir. Processor 212 shuts down pump 206, for example, when thepressure of the gas in weighing segments 218 ₁, 218 ₂, 218 ₃, . . . ,218 _(N) and reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M)reaches zero.

With reference to FIG. 4B, reference segments 220 ₁, 220 ₂, 220 ₃, . . ., 220 _(M) are filled with gas until the gas therein reaches apredetermined pressure. To that end, processor 212 directs valesprocessor 212 directs valves 224, 228 and 230 to the open state thereofand directs valves 226, 232, and 234 to the closed state thereof.Processor 212 then activates pump 206 and the gas flows from the gasreservoir, through valve 234, pump 206, valve 232 and valve 234 intoreference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M). When thepressure of the gas in reference segments 220 ₁, 220 ₂, 220 ₃, . . . ,220 _(M) reaches a predetermined level, processor 212 shuts down pump206.

With reference to FIG. 4C, the gas in reference segments 220 ₁, 220 ₂,220 ₃, . . . , 220 _(M) is transferred to weighing segments 218 ₁, 218₂, 218 ₃, . . . , 218 _(N). To that end, processor 212 directs valves228, 232 and 234 to the open state thereof and valves 224, 226 and 230to the closed state thereof. Processor 212 then activates pump 206 andthe gas flows from reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220_(M) flows through valve 232, pump 206, valve 226 and valve 224 intoweighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N).

Thereafter, reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M)similar to as described above in conjunction with FIG. 3B. Thereafter,with reference to FIG. 4D, processor 212 directs valves 224, 226, 228,230, 232 and 234 to the open state thereof and acquires the weighingmeasurement and the reference measurement as described above.

As mentioned above, valve assembly 204 (FIGS. 4A-4D) may be implementedwith three three-way valves. Specifically the valve assembly may beimplemented with three three-way valves where each valve has five states(i.e., all ports are closed, all ports are open and each pair of portsis open). Reference is now made to FIGS. 5A-5D, which are schematicillustrations of a valve assembly 250 connected to a pump 252, inaccordance with a further embodiment of the disclosed technique. Port254 is fluidally coupled with weighing segments (not shown), port 256 isfluidally coupled with reference segments (not shown) and port 258 isfluidally coupled with a gas reservoir (e.g., ambient air—not shown).FIG. 5A depicts the states of the valves when the weighing and referenceare being emptied. FIG. 5B depicts the state of the valves when thereference segments are being filled with gas. FIG. 5C depicts the stateof the valves when the gas is being transported from the referencesegments to the weighing segments and FIG. 5D depicts the state of thevalves when weight is being measured.

Reference is now made to FIGS. 6A-6D, which are schematic illustrationsof a weighing mattress, generally referenced 300, constructed andoperative in accordance with another embodiment of the disclosedtechnique. Weighing mattress 300 includes a plurality of weighingsegments, such as weighing segment 302 and a plurality of referencesegments, such as weighing segment 304, interleaved between the weighingsegments. With reference to FIG. 6A, each weighing segment includes arespective fluid inlet/outlet such as fluid inlet/outlet 306. Eachreference segment also includes a respective fluid inlet/outlet such asfluid inlet/outlet 308. The weighing segments are fluidally coupledtherebetween with weighing connectors, such as weighing connected 310which connects the fluid inlet/outlet of each adjacent pair of weighingsegments. Similarly, the reference segments are fluidally coupledtherebetween with reference connectors, such as weighing connected 312which connects the fluid inlet/outlet of each adjacent pair of referencesegments.

With reference to FIG. 6B, weighing mattress 300 is depicted placed on abed 314. Also a weight sensor 316 is fluidally coupled with the weighingsegments and a reference sensor 318 is fluidally coupled with thereference segments. With reference to FIGS. 6C and 6D, depicted thereinare isometric views of one side of weighing matters 300, placed on bed314, and a mattress 320 placed on top of weighing mattress 300. FIG. 6Cdepicts one side of weighing mattress 300 and FIG. 6D depicts the otherside of weighing mattress 300.

Reference is now made to FIG. 7, which is a schematic illustration of aweighing mattress, generally referenced 400, constructed and operativein accordance with a further embodiment of the disclosed technique.Weighing mattress 400 is divided into a plurality of inflatablesections, such as sections 402 ₁ and 402 ₂. Each section is coupled withan adjacent section. Each section is welded such as to create astructure of two interleaved rakes. The fingers of one rake constituteweighing segments and the base of this rake fluidally couples theweighing segments. The fingers of the other rakes constitute referencesegments and the base of this other rake fluidally couples the referencesegments. Each rake in each section is independently inflatable. Theinflatable rake, corresponding to the weighing segments, is fluidallycoupled with a corresponding rake in an adjacent section via connectors,such as connectors 408, which are coupled with the fluid inlet/outletsof each rake. The inflatable rake, corresponding to the referencesegments, is fluidally coupled with a corresponding rake in an adjacentsection via connectors, such as connectors 410, which are coupled withthe fluid inlet/outlets of each rake.

Reference is now made to FIG. 8, which is a schematic illustration of aweighing mattress, generally referenced 450, constructed and operativein accordance with another embodiment of the disclosed technique.Weighing mattress 450 is place on a bed 452. Weighing mattress 450includes a plurality of weighing segments such as weighing segment 454and a plurality of reference segments such as reference segment 456. Theweighing segments and the reference segments exhibit the same thickness.However, only the weighing segments are affected by the weight of theobjected, since the weighing segments are positioned on steps, such asstep 458 (e.g., made from Styrofoam). The weighing segments and thereference segments are coupled with the mattress, for example, withstraps, which are coupled (e.g., glued or welded) to a base.

In some scenarios, the accuracy of the weight scale mattress may beaffected by a heat source (e.g., a human hand) which comes into contactor is located in proximity to the weighing mattress, more so if the heatsource effects either the weighing segments or the reference segments.To reduce the effects of such a heat source, the weighing and referencesegments may be covered with thermal isolation foils. These isolationfoils reduce the effects of a heat source which may come into contactwith the mattress weight scale. Reference is now made to FIG. 9, whichis a schematic illustration of a weighing mattress, generally referenced500, in accordance with a further embodiment of the disclosed technique.Weighing mattress 500 is placed on top of a bed 502. Weighing mattress500 includes a plurality of weighing segments such as weighing segment504 and a plurality of reference segments such as reference segment 506.The weighing segments and reference are covered with an isolation foilor foils, such as isolation foil 502. Isolation foil 508 is made, forexample, from aluminum.

As mentioned above, measuring the pressure in the reference segments anddetermining a difference measurement alleviates the effects ofenvironmental conditions on the pressure of the fluid in the weighingmattress. However, it is noted that employing a weighing mattress with athermal coefficient of zero also alleviates the effects of theenvironmental conditions. A weighing mattress which exhibits a thermalcoefficient of zero may be achieved by employing materials and fluids ofpositive and negative thermal coefficients.

In typical weighing systems, it is desirable to reference the sensorbefore performing a weight measurement. Referencing the weight sensorsrelates to associating a signal output from the sensor with a referenceweight (e.g., the zero weight). Referencing the weight sensorsalleviates errors in the sensor output signal (e.g., due to changestemperature, or drift in the sensor output signal). Typically,referencing the sensors entail lifting the patient from the bed,referencing the sensors, and returning the patient to the bed. Accordingto the disclosed technique, the sensors may be referenced withoutlifting the patient off the bed (i.e., the patient remains lying on themattress), by detaching the load of the patient from the weight sensors.Referring back to FIG. 4A, reference sensor 210 is referenced bycompletely deflating reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220_(M) and inflating weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218_(N) such that the patient is detached from reference segments 220 ₁,220 ₂, 220 ₃, . . . , 220 _(M) (i.e., the patient does not come intocontact with reference segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M)and does not apply weight thereon) and reference sensor 210 isreferenced. Similarly, weight sensor 208 is referenced by completelydeflating reference weighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218_(N) and inflating segments 220 ₁, 220 ₂, 220 ₃, . . . , 220 _(M) suchthat the patient is detached from weighing segments 218 ₁, 218 ₂, 218 ₃,. . . , 218 _(N) (i.e., the patient does not come into contact withweighing segments 218 ₁, 218 ₂, 218 ₃, . . . , 218 _(N) and does notapply weight thereon) and weight sensor 208 is referenced.

Referencing the sensors by detaching the patient from the weight sensors(i.e., either the sensor themselves, or elements connected to thesensors such as the weighing and reference segments), may be appliedwhen the weight of the patient is measured, for example, withload-cells. To that end, at least one vertical separator is placed underthe mattress. The vertical separator detaches the mattress from theload-cells such that no weight is applied on the load-cells. Theload-cells are referenced and vertical separator returns the mattressagain on the load-cells. The vertical separator may be one or moreinflatable elements (e.g., a gas tube, an inflatable mattress), one ormore hydraulic pistons, one or more pneumatic pistons one or moreelectric pistons and the like.

Reference is now made to FIGS. 10A, 10B and 10C, which are schematicillustrations of a weight scales system, generally referenced 550,constructed and operative in accordance with another embodiment of thedisclosed technique. In general, weight scale system 500 includes a bedsection. The bed section includes a plurality of load-cells 552 ₁, 552₂, 552 ₃, 552 ₄, and 552 ₅, a lower platform 554, an upper platform 556and a vertical separator 558. In FIGS. 10A-10C, vertical separator isexemplified as an inflatable element. Weight scale system 500 furtherincludes a pump 560, a controller 562, a user interface 563 and a memory565. Load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅ are positioned onlower platform 554 and optionally mechanically coupled thereto (e.g.,either with glue, screws, or hoop-and-loop straps). Vertical separator558 is placed on lower platform 554 but not on top of load-cells 552 ₁,552 ₂, 552 ₃, 552 ₄, and 552 ₅. Upper platform 556 is placed aboveload-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅. As a result, verticalseparator 558 is positioned between lower platform 554 and upperplatform 556. Upper platform 556 may further include aligning elementsat the bottom side thereof, such as aligning element 568, for aligningupper platform 556 with load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552₅, such that load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅ arepositioned at the corresponding positions thereof under upper platform566. Aligning elements such as alignment element 568 may be embodied,for example, as alignment wedges. Also, upper platform 556 may be madeof metal, wood, plastic or polycarbonate materials and may be embodiedas a frame or a plate.

Pump 560 is coupled with controller 562 and fluidally coupled withinflatable element 558. Each one of load-cells 552 ₁, 552 ₂, 552 ₃, 552₄, and 552 ₅ is coupled with controller 562. However, for the sake ofclarity of FIGS. 10A-10C only load-cells 552 ₁ and 552 ₅ are depicted ascoupled with controller 562. Controller 565 is further coupled with userinterface 563 and with memory 565. A mattress 564 may be placed on topupper platform 556 and a patient 566 may lie down on top of mattress564. Following is a description of the process of referencing load-cells552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅.

With reference to FIG. 10A, load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and552 ₅ are to be referenced (i.e., associated with a referenced weight).To that end, controller 562 directs pump 560 to pump gas (e.g., air,carbon dioxide and the like) into vertical separator 558 from an gassupply (e.g., ambient air or a gas tank). Vertical separator 558inflates and separates upper platform 556, along with mattress 564 andpatient 566, from load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅(i.e., such that upper platform 556 does not come into contact withload-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅) and the weightassociate with upper platform 556 (the tare weight and the weight ofpatient 566) is not applied on load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄,and 552 ₅. In other words, vertical separator 558 detaches upperplatform 556 and the load placed thereon from load-cells 552 ₁, 552 ₂,552 ₃, 552 ₄, and 552 ₅ such that the weight associated with upperplatform 556 is not applied on load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄,and 552 ₅.

With reference to FIG. 10B, vertical separator 558 has been inflated andupper platform 556, along with mattress 564 and patient 566 are detachedfrom load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅. Controller 562acquires measurements from load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and552 ₅ and associated these measurements with a reference weigh, forexample, the zero weight (i.e., referencing the load-cells).

With reference to FIG. 10C, after load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄,and 552 ₅ have been referenced, controller 562 directs pump 560 to pumpgas out of vertical separator 558 (i.e., deflate vertical separator 558)until upper platform 556 is lowered on top of load-cells 552 ₁, 552 ₂,552 ₃, 552 ₄, and 552 ₅, along with mattress 564 and patient 566, untilupper platform 556 re-attaches load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄,and 552 ₅ such that the weight associated with upper platform 556 fullyapplied on load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅.

In general, controller 562 said directs pump 560 to operate the bedsection, via vertical separator 558 in at least two modes, a referencingmode and a weighing mode. In the referencing mode, vertical separator558 detaches upper platform 556 from load-cells 552 ₁, 552 ₂, 552 ₃, 552₄, and 552 ₅, thereby enabling the referencing of load-cells 552 ₁, 552₂, 552 ₃, 552 ₄, and 552 ₅. In the weighing mode, vertical separator 558re-attaches upper platform 556 with load-cells 552 ₁, 552 ₂, 552 ₃, 552₄, and 552 ₅, such the weight associated with upper platform 556 isfully applied on load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅.

It is noted although five load-cells are depicted in FIGS. 10A-10C, thenumber of load-cells is not limited thereto and may larger or smalleraccording to design consideration. Also, although only a single verticalseparator is referred to in FIGS. 10A and 10B, the number of verticalseparators is not limited thereto and may larger according to designconsideration. In general, each load-cell, each pair of load-cells oreach group of four load-cells may be connected to a Wheatstone bridge.In other words, the load-cells may be connected to Wheatstone bridges ina quarter bridge, half bridge or full bridge configurations. The outputsof the Wheatstone bridges are sampled (e.g., with analog to digitalconverters) and summed (e.g., by controller 562). Controller 562presents the weight of the patient 566 to a user via user interface 563.

When measuring the weight of a patient such as patient 566, the totalweight of mattress 564 and upper platform 556, as well as of additionalobjects (e.g., pillows, blankets, sheets and the like), also referred toas tare weight, should be known. When measuring the weight of a patient,this tare weight is subtracted from the weight measured by theload-cells. The tare weight is determined when the patient is notlocated on the mattress. The load-cells are referenced similar to asdescribed above, prior to measuring the tare weight. Alternatively, theweight of mattress 564, upper platform 556 and of other individualadditional objects (e.g., the weight of each pillow, the weight of eachblanket) may be measured prior to use and stored in memory 565. A usercan indicated, via user interface 562 the number of blankets and pillowsplaced on the bed. Furthermore, if for example, the patient requests anadditional blanket or an additional blanket, the user updates the tareweight by indicating, via user interface 563, that a blanket or a pillowhas been added.

Following is an example of a bed section according to a furtherembodiment of the disclosed technique. Reference is now made to FIGS.11A, 11B and 11C, which are schematic illustration of an exemplary bedsection, general referenced 600, constructed and operative in accordancewith a further embodiment of the disclosed technique. FIG. 11A depictsan isometric view of bed section 600, FIG. 11B depicts a top view of bedsection 600 and FIG. 11C depicts a side view of bed section 600. Bedsection 600 is located on a bed 602. Bed section 600 includes a lowerplatform 604, an upper platform 606, a plurality of load-cells such asload-cell 608 and two vertical separators 610 ₁ and 610 ₂. In theexample brought forth in FIGS. 11A-11C, upper platform 606 is embodiedas a frame and may include load-cells enclosures such as load-cellenclosure 612. Alternatively, lower platform 604 includes load-cellsenclosures. Also in the example brought forth in FIGS. 11A-11C, each oneof vertical separators 610 ₁ and 610 ₂ is embodied as a gas tube.

In general a weight scale system such as described above in conjunctionwith FIGS. 10A-10C and 11A-11C includes at least one vertical separator.When embodied as an inflatable element, the vertical separator mayexhibit a selected form such as a straight line, the form of the letter‘S’, the form of a figure ‘8’, the form of the letter ‘H’ and the like.When a plurality of inflatable elements are employed, all the inflatableelements may be fluidally coupled with a single pump. Alternatively,each inflatable element may be fluidally coupled with a respective pumpor each group of inflatable elements may be fluidally coupled with arespective pump. Also, the lower platform (e.g., lower platform554—FIGS. 10A-10C or lower platform 604—FIGS. 11A-11C) and the upperplatform (e.g., upper platform 556—FIGS. 11A-11C or upper platform606—FIGS. 10A-10C) may be partitioned into corresponding sections, suchthat the lower platform and the upper platform are foldable.

When detaching the upper platform from the load-cells, the upperplatform may be raised above the load-cells or alternatively, the lowerplatform may be lowered. Reference is now made to FIGS. 12A and 12B,which are a schematic illustration of an exemplary bed section,generally referenced 700, constructed and operative in accordance withanother embodiment of the disclosed technique. Bed section 700 islocated on a bed 702. Bed 702 includes bed section supports 704 ₁ and704 ₂. A mattress 716 is placed on top of upper platform 708 and apatient 718 may lies down on mattress 716. Bed section 700 includes alower platform 706, an upper platform 708, a plurality of load-cells 710₁, 710 ₂ and 710 ₃ and two vertical separators 712 ₁ and 712 ₂.Load-cells 710 ₁, 710 ₂ and 710 ₃ are positioned on lower platform 706and optionally mechanically coupled thereto. Upper platform 708 mayinclude alignment elements such as alignment wedge 714. Verticalseparators 712 ₁ and 712 ₂ are mechanically coupled with bed sectionsupports 704 ₁ and 704 ₂ respectively.

With reference to FIG. 12A, upper platform 708 is supported byload-cells 710 ₁, 710 ₂ and 710 ₃ such that upper platform 708, mattress564, and patient 566 apply their full weight on load-cells 710 ₁, 710 ₂and 710 ₃. With reference to FIG. 12B, vertical separators lowered lowerplatform 706 along with load-cells 710 ₁, 710 ₂ and 710 ₃ such thatupper platform 708 and load-cells 710 ₁, 710 ₂ and 710 ₃ are separatedone from the other, upper platform 708 rests on bed section supports 704₁ and 704 ₂, and no weight is applied on load-cells 710 ₁, 710 ₂ and 710₃. Thereafter, the load-cell can be referenced and the verticalseparators 712 ₁ and 712 ₂ raise lower platform 706, long withload-cells 710 ₁, 710 ₂ and 710 ₃ such that the upper platform 708 andthe load placed thereon apply their full weight on load-cells 710 ₁, 710₂ and 710 ₃.

As mentioned above, lower platform and the upper platform of a bedsection of a weight scale system according to the disclosed techniqueare partitioned into corresponding sections, such that the lowerplatform and the upper platform are foldable. When employed formeasuring the weight of a patient in a hospital bed, this enables thebed section fold when one of the bed sections is inclined. Nevertheless,a weight scale system according to the disclosed technique can stilldetermine the weight of the patient when one of the bed sections isinclined. Reference is now made to FIGS. 13A and 13B. FIG. 13A is aschematic illustration of an exemplary bed section, general referenced720, constructed and operative in accordance with a further embodimentof the disclosed technique. FIG. 13B is a schematic illustration of anexemplary weight sensor assembly, general referenced 732, constructedand operative in accordance with a further embodiment of the disclosedtechnique.

With reference to FIG. 13A, bed section 720 is placed on a support 721of bed 722. A mattress 724 is placed on top of bed section 720. Apatient 724 may be lying down on mattress 722. Bed section 720 includesa lower platform 728, an upper platform 730, and a plurality of weightsensor assemblies such as weight sensor assembly 732. Bed section 720further includes at least one vertical separator (not shown in FIG. 14for the sake of clarity). In FIG. 14A, the segment of bed section 720 onwhich the upper body of patient 726 is located is inclined at an anglerelative to support 721.

With reference to FIG. 13B, weight sensor assembly 732 includes twoweight sensors, first weight sensor 734 ₁ (also referred to as“horizontal sensor”), second weight sensor 734 ₂ (also referred to as“vertical sensor”) and an L-shaped bracket 736 (i.e., a bracket wherethe bracket plates are connected perpendicularly one with respect to theother). L-shaped bracket 736 includes two plates, first plate 737 ₁ andsecond plate 737 ₂. First plate 737 ₁ and second plate 737 ₂ areperpendicular one with respect to the other. FIG. 14B depicts a sideview of L-shaped bracket 736. First weight sensor 734 ₁ is attached tolower frame 728 (i.e., either directly or in-directly via a sensorsenclosure) and to the outer face of first plate 737 ₁, such that firstweight sensor 734 ₁ measures any force applied perpendicular to firstplate 737 ₁ (i.e., in the direction of arrow 820). Second weight sensor734 ₂ is attached to the inner face of second plate 737 ₂, such thatsecond weight sensor 734 ₂ measures any force applied perpendicular tosecond plate 737 ₂ (i.e., in the direction of arrow 822). L-shapedbracket 736 decomposes the force applied on the inclined segment of bedsection 720 to the components thereof (i.e., the inclined segment of bedsection 720).

Upper platform 730 is positioned on top of second weight sensor 734 ₂.The weight of patient 726, lying down on matters 724, applies a force inthe direction of arrow 738 (i.e., perpendicular to support 721). Firstweight sensor 734 ₁ measures the component in the direction of arrow820. Second weight sensor 734 ₂ measures the component in the directionof arrow 822. The magnitude of the vector sum (i.e., the root of the sumof the squares) of these two measurements is the magnitude of the forceapplied by patient 726 on sensor assembly 732. Sensor assemblies, suchas weight sensor assembly 732 may also be connected to Wheatstonebridges in a quarter bridge, half bridge or full bridge configuration.When a plurality of sensor assemblies such as sensor assembly 732 aregrouped (i.e., in groups of twos or fours), all the horizontal sensorsin the group are connected to one Wheatstone bridge and all the verticalsensors are connected to another Wheatstone bridge. The output from eachWheatstone bridge is sampled and the magnitude of the vector sum ofthese outputs is determined.

Reference is now made to FIG. 14 which is a schematic illustration of aweight scale system, generally reference 750, constructed and operativein accordance with another embodiment of the disclosed technique. System750 includes a controller 752, a bed section 754, a vertical separatoractuator 756, a memory 758 and a user interface. Bed section 754includes an upper platform 762, a vertical separator 764, weight sensorassemblies 766 and a lower platform 768. Bed section 754 may be any oneof the bed sections described above in conjunction with FIGS. 10A-10C,11A-11C and 12A-12B. Vertical separator may be an inflatable element(e.g., inflatable element 558—FIGS. 10A-10C) or inflatable elements(e.g., inflatable element 610 ₁ and 610 ₂—FIGS. 11A-11C), a hydraulicpiston, a pneumatic piston, an electric piston, an electricscissors-jack and the like. Vertical separator actuator 756 correspondsto the type of vertical separator. For example, when vertical separator764 is an inflatable element, vertical separator actuator 756 is a gaspump. When vertical separator 764 is a hydraulic piston or a pneumaticpiston, vertical separator actuator 756 is a hydraulic or pneumatic pumprespectively. When vertical separator 764 is an electric piston or anelectric scissors-jack, vertical separator actuator 756 is an electricmotor. Each of weight sensor assemblies 766 includes at least one weightsensors (e.g., load-cells 552 ₁, 552 ₂, 552 ₃, 552 ₄, and 552 ₅—FIGS.10A-10C, sensor assembly 732—FIG. 13B or a combination thereof). Memory758 stores calibration data, and may also store information relating tothe weight of individual object typically placed on upper platform 762(e.g., a mattress, a pillow, sheets, a blanket and the like). Memory 758may further store past measurements of the object. User interface 760presents data to the user. For example, user interface presents the userwith the weight of the object. User interface 760 may receiveinformation relating to objects placed on upper platform 762 thusenabling to update the tare weight placed on upper platform 762.

Controller 752 is coupled with vertical separator actuator 756, with theweight sensors in weight sensor assemblies 766, with memory 758 and withuser interface 760. Vertical separator actuator 756 is further coupledwith vertical separator 764. In operation upper platform 762 and theload placed thereon (i.e., the object to be measured and the tareweight) apply their full weight on weight sensor assemblies 766.Controller 752 acquires a measurement of the weight of the load appliedon weight sensor assemblies 766 and subtracts the tare weight todetermine the weight of the object (e.g., a patient in a hospital bed).When weight sensor assemblies 766 are employed for measuring the weightof an object positioned on an inclined surface, weight sensor assembliesinclude two weight sensors such as described above in conjunction withFIGS. 13A and 13B, controller 752 determines the vector sum of each twoweight sensors in weight sensor assemblies 766.

When referencing the weight sensor, controller 752 directs verticalseparator actuator 756 to operate vertical separator 764 so as to detachupper platform 762, and the load placed thereon, from weight sensorassemblies 766 such that no weight is applied on the weight sensors. Adescribed above, when detaching upper platform 762 from weight sensorassemblies 766, vertical separator 764 may raise upper platform 762 orlower lower platform 768. When upper platform 762 is detached fromweight sensor assemblies 766, controller 752 references the weightsensors in the weight sensor assemblies 766 (i.e., controller 752associates the measurements from weight sensor assemblies 766 with areference weight). Thereafter, controller 752 directs vertical separatoractuator 756 to operate vertical separator 764 so as to re-attach upperplatform 762 with weight sensors assemblies 766, such that the weightassociated with upper platform 762 is fully applied on the weight sensorassemblies 766.

In general, controller 752 said vertical separator actuator 756 tooperate bed section 754, via vertical separator 764 in at least twomodes, a referencing mode and a weighing mode. In the referencing mode,vertical separator 764 detaches upper platform 761 from weight sensorassemblies 766, thereby enabling the referencing of the weight sensors.In the weighing mode, vertical separator 764 re-attaches upper platform762 with weight sensor assemblies, such the weight associated with upperplatform 762 (i.e., the tare weight and the weight of the object) isfully applied on weight sensors.

Similar to as described above, when measuring the weight of an object,controller 752 samples (e.g., with analog to digital converters) themeasurements from the weight sensors or group of sensors (e.g.,depending on the configuration of the Wheatstone bridges) and sums thesemeasurements. When sensor assemblies 766 are similar to sensorassemblies 732 (FIGS. 13A and 13B), controller 752 determines themagnitude of the vector sum of the measurements from horizontal sensorsand the vertical sensor as described above in conjunction with FIGS. 13Aand 13B). Controller 752 presents the weight of the object to a user viauser interface 760. Controller 752 may further be connected to anetwork, thereby transmitting the measured weight to a remote location.For example, when measuring the weight of a patient in a hospital bed,controller 752 transmits (e.g., via a network adapter) the weight to thenurse station. Alternative, controller 752 transmits the weight to aportable device (e.g., a smartphone, a tablet computer and the like).Furthermore, when weight scale system 700 is employed to measure theweight of patient in a hospital bed, controller 752 may detect that thepatient has left the bed (e.g., when the measured weight decreases atleast at a predetermined rate and drops below a threshold value for apredetermined time-period). Controller 752 may than generate an alarm,for example, via user interface 760 or via the network. Also when weightscale system 700 is employed to measure the weight of patient in ahospital bed, weight scale system 700 may be employed to measure theliquid balance of a patient by entering (e.g., via user interface 760)the weight of the liquids administered to the patient, and weighing thepatient with and without the waste collection bag. The differencebetween the weight of the patient with and without the waste collectionbag results in the weight of the waste. The difference between theweight of the liquids administered to the patient and the weight of thewaste is indicative of the patient liquid balance.

Reference is now made to FIG. 15, which is a schematic illustration of amethod for referencing weight sensors in a bed section, operative inaccordance with a further embodiment of the disclosed technique. Inprocedure 800, the weight sensors are detached from the upper platformof the bed section such that no load is applied on the weight sensors.According to one alternative, the upper platform is raised above theweight sensors by a vertical separator. According to anotheralternative, the lower platform is lowered by the vertical separator.With reference to 13, controller 752 directs vertical separator actuator756 to operate vertical separator 764 so as to detach upper platform762, and the load placed thereon from weight sensor assemblies 766.

In procedure 802, the weight sensors are referenced. When referencingthe weight sensors, the measurement from the weight sensors isassociated with a reference weight (e.g., the zero weight). Withreference to FIG. 13, controller 752 references the weight sensor inweight sensor assemblies 766.

In procedures 804, the upper platform is re-attached with the weightsensors such that the weight associated with the upper platform (e.g.,the weight of the platform, the patient and of additional objects placedon the upper platform) is fully applied on the weight sensors (i.e.,either lower upper platform or raise lower platform). With reference toFIG. 13, controller 752 directs controller 752 directs verticalseparator actuator 756 to operate vertical separator 764 so as tore-attach upper platform 762 with weight sensors 766 such that upperplatform 762 and the load placed thereon apply their full weight onweight sensors 766.

It will be appreciated by persons skilled in the art that the disclosedtechnique is not limited to what has been particularly shown anddescribed hereinabove. Rather the scope of the disclosed technique isdefined only by the claims, which follow.

1. A weight scale system for measuring the weight of at least oneobject, the weight scale system comprising: a bed section including: alower platform; an upper platform, for bearing the weight of said atleast one object; at least one weight sensor assembly including at leastone weight sensor, said at least one weight sensor assembly beinglocated on said lower platform, said at least one weight sensor beingoperable to measure weight applied thereon; and at least one verticalseparator, operable to detach said upper platform from said at least oneweight sensor assembly; at least one vertical separator actuator,coupled with said vertical separator, operable to operate said verticalseparator; and a controller, coupled with said at least one weightsensor and with said vertical separator actuator, prior to referencingsaid at least one weight sensor, said controller directing said verticalseparator actuator to operate said bed section in at least two modes: areferencing mode in which said vertical separator detaches said upperplatform from said at least one weight sensor assembly, thereby enablingthe referencing of said at least one weight sensor; and a weighing modein which said vertical separator re-attaches said upper platform withsaid at least one weight sensor assembly, such that the weightassociated with said upper platform is fully applied on said at leastone weight sensor.
 2. The weight scale system according to claim 1,wherein said vertical separator is at least one inflatable element andsaid vertical separator actuator is at least one gas pump, fluidallycoupled with said inflatable element.
 3. The weight system according toclaim 2, wherein said vertical separator includes at least two airtubes.
 4. The weight scale system according to claim 2, wherein saidupper platform includes alignment elements at the bottom side thereof,for aligning said upper platform with said at least one weight sensor,such that said at least one weight sensor is positioned at thecorresponding position thereof under said upper platform.
 5. The weightscale system according to claim 1, wherein said at least one weightsensor is a load-cell.
 6. The weight scale system according to claim 1,wherein said vertical separator raises said upper platform so as todetach said upper platform said from said at least one weight sensorassembly.
 7. The weight scale system according to claim 1, wherein saidvertical separator lowers said lower platform so as to detach said upperplatform said from said at least one weight sensor assembly.
 8. Theweight scale system according to claim 1, wherein said bed section ispositioned on a hospital bed, for measuring the weight of a patientlying down on said hospital bed; and wherein said vertical separatordetaches said upper platform said from said at least one weight sensorassembly when said patient is lying down on said hospital bed.
 9. Theweight scale system according to claim 1, wherein said at least oneweight sensor assembly includes two weight sensors and an L-shapedbracket, said L-shaped bracket includes two plates perpendicular onewith respect to the other, a first weight sensor of said two weightsensors is attached to said lower frame and to the outer face of a firstplate, such that said first weight sensor measures any force appliedperpendicular to said first plate, a second weight sensor of said twoweight sensors is attached to the inner face of the second plate, suchthat said second weight sensor measures any force applied perpendicularto said second plate, and wherein the weight of the object is applied onsaid second weight sensor.
 10. The weight scale system according toclaim 1, wherein said at least one weight sensor assembly includes asensor enclosure.
 11. A method for referencing at least one weightsensor in a weight scale system, the method comprising the proceduresof: detaching an upper platform of a bed section of a weight scale fromsaid at least one weight sensor such that no weight is applied on saidat least one weight sensor, the bed section including a lower platform,said upper platform for bearing the weight of at least one object, saidat least one weight sensor being located on said lower platform andoperable to measure weight applied thereon; referencing said at leastone weight sensor; and re-attaching the upper platform to said at leastone weight sensor such that the upper platform and the load thereonapply their full weight on said at least one weight sensor.
 12. Themethod according to claim 11, wherein said upper platform is liftedabove said at least one weight sensor.
 13. The method according to claim11, wherein said lower platform is lowered so as to detach said upperplatform from said at least one weight sensor.
 14. The weight scalesystem according to claim 1, wherein said a least one weight sensor is aload-cell.
 15. The method according to claim 11, wherein said bedsection is positioned on a hospital bed, for measuring the weight of apatient lying down on said hospital bed; and wherein said detachingoccurs when said patient is lying down on said hospital bed.